Polymers obtained through polymerization of a compound having a heteroatom-containing five-membered or aromatic-ring structure, such as pyrrole, thiophene, aniline, etc., is suitable as electrically conductive material, so that studies on the polymers are actively proceeding. Electric conductivity of these polymers can be freely controlled by changing the amount of a dopant, an ionic material, accordingly, practical application of these polymers to various electrodes, sensors, primary cells, secondary cells, solid electrolytic capacitors, antistatic agents, etc. has been attempted so far.
In particular, poly (3,4-alkylenedioxythiophene) derivatives are known as having a high conductivity, and various poly (3,4-alkylenedioxythiophene) derivatives have been reported (L. Groenendaal et al., Electrochemistry of Poly (3,4-alkylenedioxythiophene) Derivatives, Advanced Materials 2003, Vol. 15, No. 11, p. 855-879). However, solubility of the obtained poly (3,4-alkylenedioxythiophene) derivatives are not so high, so that there is somewhat difficulty in processability in film formation, accordingly improvement in solubility has been awaited.